The present invention relates to a pneumatic tire, more particularly to a block pattern having a specific groove arrangement being capable of improving noise during on-road running, while maintaining a good road grip during off-road running.
Usually, 4WD vehicles including Recreational Vehicles are equipped with radial tires designed for off-road use such as dirt roads, muddy roads, snowy roads and the like. However, 4WD vehicles especially Recreational Vehicles also have many opportunities to run on well paved roads such as highway, freeway and the like.
On the other hand, the tread pattern mostly used in the off-road tires is a block pattern made up of blocks divided by relatively wide grooves. In such a block pattern tire, as the space between the blocks is wide, steering stability and ride comfort especially noise performance under on-road conditions are not good.
The on-road performance may be improved if the grooved area in the tread is decreased, but, it deteriorates off-road performance, e.g. grip performance such as traction, braking and cornering grip, and discharge of mud, snow, etc. packed into the grooves.
It is therefore, an object of the present invention to provide a vehicle tire, in which on-road performance especially noise is improved without deteriorating off-road performance especially grip performance so as to be used under on-road conditions as well as off-road conditions.
According to the present invention, a vehicle tire comprises
a tread provided with a circumferential groove (G) on each side of the tire equator to divide the tread into a central tread portion between the circumferential grooves and a lateral tread portion axially outside each of the circumferential grooves,
the central tread portion divided into central blocks B0 by central oblique grooves (g) extending thereacross,
the lateral tread portion provided with
first oblique grooves (ga) extending from the circumferential groove (G) to the tread edge,
second oblique grooves (gb) extending from the circumferential groove (G) to the tread edge without joining the first oblique grooves (ga) and alternating with the first oblique grooves (ga),
cross oblique groove (gc) each extending from one of the first oblique grooves (ga1) to the next first oblique groove (ga2) while crossing the second oblique groove (gb) therebetween,
inclinations of the central oblique grooves (g) and the cross oblique grooves (gc) being reverse to inclinations of the first oblique grooves (ga) and the second oblique grooves (gb) with respect to the tire equator,
whereby the lateral tread portion is divided into
first lateral blocks B1 defined as being surrounded by the circumferential groove (G), cross oblique groove (gc), second oblique groove (gb) and first oblique groove (ga1),
second lateral blocks B2 defined as being surrounded by the circumferential groove (G), cross oblique groove (gc), second oblique groove (gb) and first oblique groove (ga2),
third lateral blocks B3 defined as being surrounded by the cross oblique groove (gc), tread edge, second oblique groove (gb) and first oblique groove (ga1), and
fourth lateral blocks B4 defined as being surrounded by the cross oblique groove (gc), tread edge, second oblique groove (gb) and first oblique groove (ga2),
the number of the first lateral blocks B1, the number of the second lateral blocks B2, the number of the third lateral blocks B3 and the number of the fourth lateral blocks B4 in each said lateral tread portion and the number of the central blocks B0 being equal to each other, and
two of the cross oblique grooves (gc) meeting with one of the first oblique grooves (ga) at axially different positions.